二苯并18－冠－6辅助钡离子在1，2－二氯乙烷／水微界面转移的伏安研究

应用液／液界面微电极对二苯并１８－冠－６（ＤＢ１８－Ｃ－６）辅助推动Ｂａ~（２＋）在１，２－二氯乙烷／水（ＤＣＥ／Ｗ）界面转移的电化学过程进行了详细探讨，证明该过程遵循ＴＩＣ机理，是受扩散控制的可逆过程。通过转移电流和反应物浓度之间的线性关系，测定了Ｂａ~（２＋）以及用其它方法难以测定的ＤＢ１８－Ｃ－６。     

Simultaneous multichannel mass-specific detection for high-performance liquid chromatography using an array detector sector-field mass spectrometer

The use of a separation step, such as liquid chromatography, prior to inductively coupled plasma mass spectrometry (ICP–MS) has become a common tool for highly selective and sensitive analyses. This type of coupling has several benefits including the ability to perform speciation analysis or to remove isobaric interferences. Several limitations of conventional instruments result from the necessity to scan or pulse the mass spectrometer to obtain a complete mass spectrum. When the instrument is operated in such a non-continuous manner, duty cycle is reduced, resulting in poorer absolute limits of detection. Additionally, with scanning instruments, spectral skew can be introduced into the measurement, limiting quantitation accuracy. To address these shortcomings, a high-performance liquid chromatograph has been coupled to an ICP–MS capable of continuous sample introduction and simultaneous multimass detection. These features have been realized with a novel detector array, the focal plane camera. Instrument performance has been tested for both speciation analysis and for the elimination of isobaric interferences. Absolute limits of detection in the sub picogram to tens of picograms regime are obtainable, while the added mass dimension introduced by simultaneous detection dramatically increases chromatographic peak capacity.     

Automatic sugar analysis in the beet industry. Part I: Parameter optimization of a reversed phase HPLC carbohydrate determination

An evaluation of the most commonly used HPLC system (reversed phase octadecyl sillica gel) was undertaken in order to determine the level of certain carbohydrates in molasses produced in the refining of sugar beet. Chromatographic parameters and purification operations prior to analysis are discussed in order to develop an analytical method permitting automation of sugar determination. A Zorbax ODS column (250 × 9.4 mm), water elution, and light scattering detection allow easy determination of glucose + fructose, sucrose, and raffinose in molasses using an internal standard (maltose).     

一种西佛碱侧链型液晶高分子的合成及表征

一种西佛碱侧链型液晶高分子的合成及表征邹友思，林国良，姚青青，戴李宗，潘容华（厦门大学化学系厦门３６１００５）关键词联苯，西佛碱，侧链型，液晶高分子，基团转移聚合Ｆｉｎｋｅｌｌｎａｎｎ等提出的柔性基去偶合概念’］已在侧链型液晶高分子的研究中得到了证实...     

Intramolecular and liquid structure of 2,2,2-trifluoroethanol by X-ray diffraction

Intramolecular and liquid structure of 2,2,2-trifluoroethanol (TFE) have been investigated by x-ray diffraction at 25°C. The structural parameters for the skeleton of the molecules in the liquid phase are similar to those in the gas phase. The conformers of TFE molecules in the liquid phase are discussed. The O...O distance at about 284 pm and additional F...O one at about 302 pm were found to be characteristic for the first neighbor interactions. Various models (dimers and trimers) have been examined for analyzing the first neighbor structure. The liquid structure was explained in terms of small clusters consisting of two to three molecules rather than of a more extended polymeric network.Central Research Institute for Chemistry of the Hungarian Academy of Sciences, Budapest, P. O. Box 17, H-1525, Hungary.     

Solid-phase synthesis of liquid crystalline isoxazole library

Combinatorial library of isoxazoles was prepared by 1,3-dipolar cycloaddition on solid support. p-Cyano derivatives showed nematic and/or smectic A phases. A bilayer smectic phase for 2h is proposed by the combination of molecular mechanics calculation and X-ray diffraction experiment.     

Sensitive trace enrichment of environmental andiandrogen vinclozolin from natural waters and sediment samples using hollow-fiber liquid-phase microextraction

The presence of vinclozolin in the environment as far as the endocrine disruption effects in biota are concerned has raised interest in the environmental fate of this compound. In this respect, the present study attempts to investigate the feasibility of applying a novel quantitative method, liquid-phase microextraction (LPME), so as to determine this environmental andiandrogen in environmental samples such as water and sediment samples. The technique involved the use of a small amount (3 microL) of organic solvent impregnated in a hollow fiber membrane, which was attached to the needle of a conventional GC syringe. The extracted samples were analyzed by gas chromatography coupled with electron-capture detection. Experimental LPME conditions such as extraction solvent, stirring rate, content of NaCl and pH were tested. Once LPME was optimized, the performance of the proposed technique was evaluated for the determination of vinclozolin in different types of natural water samples. The recovery of spiked water samples was from 80 to 99%. The procedure was adequate for quantification of vinclozolin in waters at levels of 0.010 to 50 microg/L (r> 0.994) with a detection limit of 0.001 microg/L (S/N= 3). Natural sediment samples from the Aliakmonas River area (Macedonia, Greece) spiked with the target andiandrogen compound were liquid-liquid extracted and analyzed by the methodology developed in this work. No significant interferences from the samples matrix were noticed, indicating that the reported methodology is an innovative tactic for sample preparation in sediment analysis, with a considerable improvement in the achieved detection limits. The results demonstrated that apart from analyte enrichment, the proposed LPME procedure also serves as clean-up method and could be successfully performed to determine trace amounts of vinclozolin in water and sediment samples.     

On-line multidimensional chromatography using packed capillary liquid chromatography and capillary gas chromatography

The introduction of selected fractions from a liquid chromatograph into a gas chromatograph has been described; however, analyses were performed by off-line experiments requiring collection and reinjection of the separate fractions or by on-line procedures where disadvantageously, only a fraction of the separated peak or a well resolved component in a mixture could be introduced into a gas chromatograph. This disadvantage is overcome by the apparatus and method described in this paper, which utilizes a multidimensional chromatography system employing a high efficiency, packed capillary LC column coupled on-line to a capillary gas chromatograph. The liquid chromatograph (so designed) can act as a highly efficient clean-up or chemical class fractionation step prior to introduction into the gas chromatograph, significantly reducing sample preparation times in many applications. Thus minor components in a complex matrix can be determined without prior sample clean-up, an example of which is the determination of polychlorinated biphenyls in a complex hydrocarbon matrix.     

Detection ofFusarium trichothecenes (nivalenol,deoxynivalenol, fusarenone and 3-acetyldeoxynivalenol) by high-performance liquid chromatography

Summary Separation and determination ofFusarium trichothecenes: nivalenol, deoxynivalenol, fusarenone and 3-acetyldeoxynivalenol, were carried out by highperformance liquid chromatography with UV detection, and methanol—water (30/70) as mobile-phase on Lichrosorb RP-18 column. Detection limits were 2, 3, 3 and 5ng per injection of nivalenol, deoxynivalenol, fusarenone and 3-acetyldeoxynivalenol, respectively. The method appears to be adequate for detection of the above trichothecenes in contaminated corn and rice as well as in cultures ofFusarium spp. A preliminary TLC purification was necessary for detection of fusarenone in corn.     

Thin-layer adsorption chromatography with mixed mobile phases. 4. Extension of Ościk's equation to heterogeneous adsorbents

In this paper the equation for thin-layer adsorption chromatography with multicomponent mobile phases, proposed by O?cik in 1965 is extended to energetically heterogeneous solid surfaces. Other forms of this equation, more convenient in practical applications, are presented. Model calculations are made for TLC with binary mobile phases according to the modified form of O?cik's equation. Finally, this equation is compared with that of Snyder.